For recent years, resin has been used for a dental prosthesis such as a bridge and a denture base for a false tooth according to development of dental resin material because resin has advantages of excellent aesthetics etc.
For example, a bridge is a dental prosthesis that is used when a part of teeth is lost and its root does not exist. This is a dental prosthesis that holds an artificial tooth in an space produced by a lost tooth, using a natural tooth (remaining tooth) remaining in one side of the space as a basis (abutment tooth) (or using natural teeth remaining in both sides of the space).
For example, a bridge is made as follows: prior to making a bridge, an abutment tooth is ground, to have a shape easy for a dental prosthesis to be attached to (for example, a frustoconical shape); an impression of a portion including a space produced by a lost tooth and the abutment tooth of the above described shape is taken, to obtain a counterdie of a shape of a portion for which a bridge is made; further, a plaster cast is made according to this impression, the shape is determined based on the plaster cast, to make the bridge out of resin.
When all the teeth are lost, dentures where artificial teeth are arranged on denture bases that cover alveolar ridges are provided. Resin is also used for these denture bases.
However, the mechanical strength of resin is lower than metal in tension and bending. Thus, a crack might form in some portion due to lack of the strength. For example, it is employed that lack of the strength is made up for by using a metallic frame together when a dental prosthesis is made using hard resin. However, this method takes a lot of effort.
In contrast, as shown in FIG. 1 of Patent Literature 1, such a bridge is suggested that a fiber-reinforced composite material for dental restorations which comprises glass fibers in the shape of a bar is applied to. According to this, lack of the strength of a bridge made of resin can be made up for.
Patent Literature 2 describes formation of a bridge with a fiber-reinforced composite material for dental restorations ([0009] of Patent Literature 2). According to this, a cavity to face a treatment site (a portion where a tooth is lost) is formed in each adjacent tooth that is positioned in either side of the treatment site where a tooth is lost; the glass reinforced composite material is cut longer than a distance between the cavities in both adjacent teeth, and is immersed in resin or the like to put resin-coating thereon; after that, both ends thereof are placed in the cavities in both adjacent teeth as the center part thereof is bent toward a gum; resin material is poured into both cavities, to be polymerized and cured along with the fiber-reinforced composite material for dental restorations to be fixed; after that, resin material is built up in the shape of a tooth on this fixed glass reinforced composite material and cured, to make a bridge.